1. Field of the Invention
The present invention relates generally to immunology and adenoviral gene therapy. More specifically, the present invention relates to immunomodulation by genetic modification of dendritic cells and B-cells.
2. Description of the Related Art
An expanding body of evidence suggests that dendritic cells (DC) play a pivotal role in the immune system [Bancheareau, J. and R. M. Steinman. 1998, Dendritic cells and the control of immunity. Nature. 392:2459]. Foremost, dendritic cells are recognized to serve as a key mediator of T-cell based immunity. Stemming from their important function, dendritic cells have been proposed for utility in a number of clinical strategies, especially vaccinations. It has become clear that genetic modification of these cells can promote immunity against pathogenic entities, both infectious and tumorigenic [Reeves, M. E., et al. 1996. Retroviral transduction of human dendritic cells with a tumor-associated antigen gene. Cancer Res. 56:5672-7]. Importantly, all of these strategies are predicated upon efficient vectors for gene delivery to dendritic cells. To this end, a number of approaches have been utilized, albeit generally with poor efficiency of gene transfer [Arthur, J. F., et al. 1997. A comparison of gene transfer methods in human dendritic cells. Cancer Gene Ther. 4:17-25; Van Tendeloo, V. F. I., et al. 1998. Nonviral transfection of distinct types of human dendritic cells: high-efficiency gene transfer by electroporation into hematopoetic progenitor- but not monocyte-derived dendritic cells. Gene Ther. 5:700-7]. One candidate has been replication defective adenoviral vector. This vector has been suggested to be well suited for clinical applications by virtue of its high titer, efficiency gene delivery and exhuberant gene expression.
In spite of these theoretical advantages, the relative resistance of dendritic cells to adenoviral vector infection has confounded obtaining the full benefit of gene based immunotherapy strategies. [Arthur, J. F., et al. 1997. A comparison of gene transfer methods in human dendritic cells. Cancer Gene Ther. 4:17-25; Dietz, A. B. and S. Vuk-Pavlovic. 1998. High efficiency adenovirus-mediated gene transfer to human dendritic cells. Blood. 91:392-8]. The phenomenon of dendritic cell resistance to adenoviral mediated gene transfer may be based upon the paucity of adenoviral entry receptors. In permissive cells, the projecting adenoviral fiber-knob protein mediates binding to the cell surface coxsackie-adenovirus receptor (CAR) followed by interaction with and internalization of the virion by either of the av integrins avb3 or avb5 [Wickham, T. J., et al. 1993. Integrins .alpha.v.beta.3 and .alpha.v.beta.5 promote adenovirus internalization but not virus attachment. 73:309-19; Bergelson, J. M., et al. 1997. Isolation of a common receptor for Coxsackie B viruses and adenoviruses 2 and 5, Science. 275:1320-3]. The present analysis has revealed an absence of CAR but adequate expression of the av integrin, .alpha.v.beta.5. High efficiency gene transfer independent of CAR expression by means of adenovirus targeted by bispecific entities to alternate cellular receptors has previously been shown [Douglas, J. T., et al. 1996. Targeted gene delivery by tropism modified adenoviral vectors. Nature Biotech. 14:1574-8]. It was postulated that a similar strategy targeting the marker CD40, expressed on dendritic cells, might enhance gene transfer to dendritic cells.
A bispecific antibody was generated through chemical conjugation of a neutralizing anti-fiber-knob monoclonal antibody to a monoclonal antibody with affinity for the dendritic cell receptor, CD40. The present invention demonstrates that adenovirus complexed with this bispecific entity mediates dramatic enhancements in gene transfer to monocyte derived dendritic cells. More importantly, an upregulation of several dendritic cell maturational markers and enhanced allo-MLR performance after infection with CD40-targeted vector was observed, indicating the vector itself possesses maturational properties.
Thus, the prior art is deficient in methods of transducing dendritic cells and B-cells for immunomodulatory purposes. The present invention fulfills this long-standing need and desire in the art.